This application is a continuation of PCT/JP02/11945 filed Nov. 15, 2002.
The present invention relates to a ceramic color composition which, after use, is suitable for reuse as a glass material, and a process for producing a ceramic color layer-coated glass plate suitable for such reuse.
Along the inside peripheral portion of a window glass of an automobile, a ceramic color layer is formed as an opaque colored layer. Such a ceramic color layer is provided so that it is present between a urethane sealant to hold the window glass along its periphery from the inside of the car and the window glass to be thereby held, in order to prevent deterioration of the urethane sealant by ultraviolet rays or to prevent terminals of heating wires, etc. provided at the inside peripheral portion of the window glass from being seen from outside.
For such a ceramic color layer, a ceramic color composition comprising a low melting point glass powder and a heat-resistant pigment powder as essential components, is formed into a paste, which is coated on a glass plate, followed by drying and firing so that it is fired to the glass plate, whereby a ceramic color layer-attached glass plate is produced. Further, as the heat-resistant pigment powder, a black one is usually employed.
Heretofore, when such an automobile has been disused, the ceramic color layer-attached glass plate used as a window glass of the automobile, has been crushed and disposed by e.g. landfill.
In recent years, in order to reduce the environmental load, it is desired to recover and not to dispose the ceramic color layer-attached glass plate of a disused automobile and to reuse it as a material (cullet) for a glass melting furnace to produce a glass plate.
As a ceramic color composition which can be reused in such a manner, JP-A-2000-505772 discloses a ceramic color composition using a manganese compound as a heat-resistant pigment powder, or JP-A-2001-89189 discloses a ceramic color composition using (Fe, Mn)2O3 of a Bixbyite structure as a heat-resistant pigment powder. However, a ceramic color layer-attached glass plate using such a ceramic color composition has had a problem such that the sinterability of the ceramic color layer is low, or the ceramic color layer looks whitish as observed through the glass plate from the side on which no ceramic color layer is fired.
It is an object of the present invention to provide a ceramic color composition which can be reused, a ceramic color paste and a process for producing a ceramic color layer-attached glass plate which can be reused, whereby such problems can be solved.